September 1, 2014

Unless global red meat and dairy product consumption is reduced, greenhouse gases resulting from food production will increase by 80 percent in the years to come, a team of researchers from the UK reported Sunday in the journal Nature Climate Change.

This dire warning comes as an increasing number of people all over the world are “adopting American-style diets, leading to a sizeable increase in meat and dairy consumption,” said BBC News environmental analyst Roger Harrabin. If this continues, the authors warn that an increasing amount of cropland will have to be converted for use by livestock to keep up with the demand.

As a result, deforestation would increase carbon emissions, increased livestock production would cause a spike in methane emissions, and more widespread fertilizer use would accelerate climate change, Harrabin said. Conversely, the authors wrote that a scenario in which all countries achieved healthier diets (marked by reduced consumption levels of sugars, fats and meat products) significantly reduced the impact on the environment.

“There are basic laws of biophysics that we cannot evade,” lead investigator Bojana Bajzelj, a research associate in the University of Cambridge’s Department of Engineering, told BBC News. “The average efficiency of livestock converting plant feed to meat is less than 3 percent, and as we eat more meat, more arable cultivation is turned over to producing feedstock for animals that provide meat for humans.”

“The losses at each stage are large, and as humans globally eat more and more meat, conversion from plants to food becomes less and less efficient, driving agricultural expansion and releasing more greenhouse gases,” she continued. “Agricultural practices are not necessarily at fault here - but our choice of food is.”

“Unless we make some serious changes in food consumption trends, we would have to completely de-carbonize the energy and industry sectors to stay within emissions budgets that avoid dangerous climate change. That is practically impossible – so, as well as encouraging sustainable agriculture, we need to re-think what we eat,” co-author Professor Pete Smith of the University of Aberdeen’s Institute of Biological and Environmental Sciences, added in a statement.

The study authors wrote that, based on current trends, food production alone will cause total greenhouse gas emissions to exceed their global targets by 2050, and that current agricultural yields will not meet the projected food demands of the expected 9.6 billion people worldwide expected to make up the world’s population by that point.

Unless our dietary habits change, Bajzelj, Smith and their colleagues said that by 2050, cropland would have expanded by 42 percent and fertilizer use would spike by 45 percent since 2009. Furthermore, 10 percent of the world’s tropical forests would be destroyed over the next 35 years, and deforestation, fertilizer use and livestock methane emissions would cause food production-related greenhouse gases to increase by nearly 80 percent.

“The report says the situation can be radically improved if farmers in developing countries are helped to achieve the best possible yields from their land,” Harrabin said. “Another big improvement will come if the world's population learns to stop wasting food. The researchers say if people could also be persuaded to eat healthier diets, those three measures alone could halve agricultural greenhouse gas levels from their 2009 level.”

“It is imperative to find ways to achieve global food security without expanding crop or pastureland. Food production is a main driver of biodiversity loss and a large contributor to climate change and pollution, so our food choices matter,” said Bajzelj.

The researchers are recommending a diet that includes just two 85 gram (three ounce) portions of red meat and five eggs per week, as well as one serving of poultry each day.

Co-author Keith Richards from the Cambridge Department of Geography explained, “This is not a radical vegetarian argument; it is an argument about eating meat in sensible amounts as part of healthy, balanced diets. Managing the demand better, for example by focusing on health education, would bring double benefits – maintaining healthy populations, and greatly reducing critical pressures on the environment.”